Hydraulic cushion device for railway vehicles

ABSTRACT

A hydraulic cushion device includes a pair of cylinders having outer closed ends positioned together for reciprocating movement between extended and contracted positions. One of the cylinders includes a piston head having a metering orifice through which a metering pin positioned on the other cylinder is movable, whereby fluid from one side of the piston head is moved to the other side thereby providing fluid cushioning action. An accumulator casing is secured to one end of the metering pin and is relatively slidably disposed in one of the cylinders. The casing includes a floating piston normally retained by means of a spring in a closed position over openings in the casing to close the same. During cushioning action of the unit fluid passes through the openings of the casing to the interior thereof, moving the piston and fluid may be stored within the casing. The piston head includes a valve element cooperating with flutes on the metering pin for by-passing fluid through the piston.

Hutchison HYDRAULIC CUSHION DEVICE FOR RAILWAY VEHICLES [75] Inventor: John W. Hutchison, Crown Point,

Ind.

[73] Assignee: Pullman Incorporated, Chicago, 111.- [22] Filed: Feb. 3, 1972 [21] Appl. No.: 223,241

[52] U.S. Cl 213/43, 188/317, 213/223, 267/65 R [51] Int. Cl. 861g 9/16 [58] Field of Search 213/8, 43, 223;

[56] References Cited UNITED STATES PATENTS 3,251,481 5/1966 Karakashjan et a1. 213/43 3,559,818 2/1971 Knippel 213/43 3,568,856 3/1972 Knippel 213/43 3,596,773 8/1971 Peterson 213/43 3,616,881 11/1971 Nicholls 188/318 3,633,763 l/l972 Peterson 213/43 3,679,069 7/1972 Shaver 213/43 3,696,894 10/1972 Brady 188/322 Primary Examiner-Drayton E. Hoffman AttorneyHilmond O. Vogel et al.

[57] ABSTRACT A hydraulic cushion device includes a pair of cylinders having outer closed ends positioned together for reciprocating movement between extended and contracted positions. One of the cylinders includes a piston head having a metering orifice through which a metering pin positioned on the other cylinder is movable, whereby fluid from one side of the piston head is moved to the other side thereby providing fluid cushioning action. An accumulator casing is secured to one end of the metering pin and is relatively slidably disposed in one of the cylinders. The casing includes a floating piston normally retained by means of a spring in a closed position over openings in the casing to close the same. During cushioning action of the unit fluid passes through-the openings of the casing to the interior thereof, moving the piston and fluid may be stored within the casing. The piston head includes a valve element cooperating with flutes on the metering pin for by-passing fluid through the piston.

' 11 Claims, 4 Drawing Figures July 3, 1973 v HYDRAULIC CUSHION DEVICE FOR RAILWAY VEHICLES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to cushioning devices and particularly to those which are adapted for end of car cushioning and which are effective both in buff and draft.

2. Description of the Prior Art The prior art includes U.S. Pat. Nos. 3,559,818, Feb. 2, 1971; 3,583,573, June 8, 1971; 3,596,773, Aug. 3, 1971 and 3,599,802, Aug. 17, 1971. The aforementioned patents are concerned with cushioning devices for railway cars wherein the excess fluid which is moved from one chamber to the other during hydraulic cushioning is received in an accumulator of the rubber flexible type.

SUMMARY OF THE INVENTION A hydraulic cushioning unit for end of car cushioning comprises a pair of telescopic cylinders having outer closed ends with one of the cylinders having a piston connected thereto to provide on opposite sides thereof a pair of chambers. The piston includes a longitudinal metering orifice. A metering pin connected to one of the cylinders extends through the metering orifice from one chamber to the other chamber and has connected at its end an accumulator casing within which a piston is slidably disposed. The piston is normally urged into a closed position over apertures in the casing during the extended or neutral position of the unit. Upon a buff impact, which contracts the unit, fluid from one chamber is discharged to the other chamber and excess fluid is forced through the apertures of the accumulator casing, moving the piston to a position to accommodate the additional fluid which is then stored in the accumulator. During the return stroke of the unit to its normal position, the piston within the accumulator is again biased over the apertures and fluid is discharged from the accumulator. The piston separating the two chambers also is provided with a novel by-pass valve which includes spring biased elements blocking flow of fluid through flutes provided on the metering pin whereby fluid is by-passed within the piston outwardly through apertures provided in the valve element during the passage of fluid from one chamber to the other.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view through a cushioning unit with a pair of telescoping cylinders in a neutral position;

FIG. 2 is a cross sectional view similar to FIG. 1 showing the cushioning unit in a contracted position;

FIG. 3 is a cross sectional view taken substantially along the line 33 of FIG. 2; and

FIG. 4 is a cross sectional view taken substantially along the line 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now particularly to FIG. I and FIG. 2, a cushioning unit 10, particularly adapted for railroad operation, includes a first cylinder 11 having an inner cylindrical surface 12. An end plate 13 is rigidly connected to the cylinder 11 to close one end thereof. A second cylinder 14 includes an inner cylindrical surface l5 and is disposed over the cylinder 11 for relative reciprocation. The cylinder 14 also includes an end plate 16 closing one end of said cylinder. A stop ring 17 is rigidly connected around the outer peripheral surface of the cylinder 14 and a coil spring 18 is held captive between the end plate 13 and the ring 17 thereby continually biasing the cylinders 11 and 14 to the neutral position disclosed in FIG. I.

The installation of the cushioning unit within the underframe ofa rail car may be similar to that disclosed inany of the aforementioned patents. The railroad car underframe generally comprises a hollow center sill, as disclosed in the above patents which may include suitable stops engaging the end plate 13 for rigidly securing one end of the cushioning unit in position. Similarly, the present end plate 16 is connected to a conventional coupler which receives the buff and draft impacts to which railway car cushion underframes are subjected in service. Since the present cushioning unit may be thus conventionally installed, it is not believed necessary to further describe such installation.

More specifically, the cushion unit 10 further includes a piston 19 which is rigidly secured to one end of the cylinder 1 1 and provides with the cylinders a first chamber 20 and a second chamber 21. The piston 19 includes a longitudinal extending bore 23 opening into an annular cavity 24 provided in the outer side 25 of the piston 19. A valve plate 26 is longitudinally slidable within the cavity 24 and includes a metering orifice 27. A retainer ring 28 limits the outer sliding movement of the valve plate 26. The piston 19 also is suitably provided around its outer peripheral surface with a seal ring 29 of a suitable plastic material engageable with the inner cylindrical surface 15 of the cylinder 14. A second cavity 30 is provided in the piston 19 in an inner side 31 thereof. The piston 19, as best shown in FIGS. 3 and 4, also is provided with a plurality of relatively small metering bores '32. A retainer ring 33 is secured within the second annular cavity 30 and a valve element 34 is slidable longitudinally within the said cavity.

As best shown in FIGS. 1 and 2 the valve element 34 comprises an intermediate plate 35, an inner plate 36 and outer plate 37, the said plates being secured together by suitable means such as rivets, etc. In FIG. 4 the intermediate plate 35 is provided with a plurality of circumferentially spaced slots 38. As shown in FIG. 3, the inner plate 36 is provided with similar slots 39 in registry with the slots 38. The outer plate 37 is also provided with identical slots 38 (not shown) which register with the slots 39, thereby providing straight through passages for the valve element 34. Referring now to FIG. 4, the intermediate plate 35 also is provided with a plurality'of pockets 40 spaced between adjacent ends of slots 38. A blocking element 41 is slidably disposed in each of the pockets 40 and is provided at its lower edges with converging surfaces 42. Each of the blocking elements 41 also includes sockets 43 in which springs 44 are disposed, the said springs 44 urging the small to the larger depth varies and thus, with the metering orifice during operation provides for a constant force travel during the operation of the cushioning unit. The provision of flutes and their relationship to the orifices is well known to the art for providing what is known as substantially constant force travel.

Referring now in particular to FIGS. 1 and 2, an accumulator chamber 50 includes a casing 51 of tubular construction. The casing 51 is provided around its outer peripheral surface with a plurality of spaced piston or seal rings 52 which are slidingly engaged with the inner surface 12 of the cylinder 11. The casing 51 includes a front wall 53 which is integrally connected to the metering pin 45. Openings 54 are provided in the front wall 53 to communicate with the chamber 21. The casing 51 also is provided with a rear wall 55 including a central vent opening 56 which communicates with a vent opening 57 on the end plate 13 to communicate the space in back of the plate and the space in back of the piston 58 within the casing 51 to the atmosphere. A sleeve 59 is rigidly connected within the casing 51 to the rear wall 55 and functions as a limit stop for the piston 58, as best shown in FIG. 2. The coil spring 60 is also held captive between the wall 55 and the movable piston 58 and urges the piston 58 to the right as indicated in FIG. 1. I

OPERATION As indicated above a cushioning unit is adapted to be secured on each of opposite ends of the center sill of a railway car underframe. The end plate 13 may be secured against longitudinal movement and the end plate 16 may be connected to a suitable yoke of a conpler assembly in conventional fashion. Assuming now that a buff impact occurs on the coupler, the cylinder 14 is moved from the neutral position to the left in FIGS. 1 and 2 whereupon fluid in the'chamber 20 is forced through flutes 47 at the metering orifice 27 in the direction of the chamber 21. The valve element or assembly 34 is moved to the left as shown in FIG. 2 and the space of the cavity 30 behind the valve element 34 which has been moved to the position shown in FIG. 2. Thus, the cavity in back of the valve element 34 receives this by-passing fluid and the same is directed through the apertures 38 and 39 into the chamber 21.

As the cushioning unit continues to close andthereby cushion the shock forces, fluid is forced into the apertures or openings 54 and in turn moves the piston 58 to the left as indicated in FIG. 2 against the action of the spring 60. Thus, the accumulator now also fills up with the excess fluid. Any air present in back of the piston 58 is free to vent through the openings 56 and 57 to the atmosphere. Thus, the action of the cushioning unit in connection with the buffing impact has been de-' scribed. The return spring 18 now is effective to return the cushioning unit to its neutral position shown in FIG. 1, whereupon, during this movement, the valve element 34 is moved to the right, as indicated in FIG. 1, and fluid now flows through the bores 32 into the cavity 24 and thus outwardly through the flutes 47 back into the chamber 20. In this movement the valve plate 26 is moved to the right as indicated in FIG. 1.

Assuming now that a draft impact on the coupler causes movement of the cylinder 14 to the right from the position shown in FIG. 1, whereupon the casing 53 is moved further, adjacent to the surface 31 of the piston 19. The remaining fluid within the cavity 21 is now directed through the bores 32 into the cavity 24 and outwardly through the flutes into the chamber 20. The valve plate 26 in the position shown in FIG. 2 blocks bores 32. However, in the other position shown in FIG. 1, fluid also flows around the peripheral edges of valve plate 26 toward and into chamber 20 since the peripheral edges of the plate may be serrated or apertured. Thus, movement of the cylinder 14 to the right in the event of a draft impact is cushioned in that the hydraulic flow of fluid through the bores 32 is restricted in metering fashion and thus provides for cushioning action. The bores 32, therefore, in the return stroke as well as during draft impacts provide a metered flow fluid from the chamber 21 to the chamber 20.

The present construction is of economical design, providing a simple and maintenance free accumulator in the form of the casing 53 and its associated parts. Metering is achieved through the metering orifice and the relative changing area of the metering flutes 47. However, in the buff impact stroke by virtue of the blocking action of the blocking elements 41 the fluid flow through the flutes is blocked in the piston area and thus fluid is by-passed to the cavity 30 behind the valve plate 34 and fluid is then discharged through the slots 38 and 29 into the chamber 21. Thus, the blocking elements 41 continue to block movement of the fluid directly into the chamber 21 and provide for a by-pass of fluid in the buff impact stroke. Further, the same is true in the draft impact stroke or return stroke in that fluid again is prevented from being discharged into the metering fluids directly from the chamber 21 by virtue of the blocking elements 41. However, in this return stroke the fluid is metered through the bores 32 so that it reaches the chamber 20. Thus, also, it is apparent that the flutes achieve their metering purpose in connection with the metering orifice in the buff impact situation but at the same time fluid flow from the flutes is not directly into the chamber 21 but is bypassed. So, as in the draft impact stroke, fluid is not directly transmitted from the chamber 21 through the flutes 47 but instead the flutes 47 are blocked and fluid flow is through the alternate route, mainly the bores 32.

Thus, it is believed that the objectives of simplicity of design resulting in a maintenance free and efficient operation have been achieved by the present construction.

What is claimed is:

1. A hydraulic cushion device for'railway cars comprising:

a first cylinder having at one end a closure plate,

a second cylinder having an open end and a second closure plate adjacent its other end,

said second cylinder being slidingly disposed relative to said first cylinder,

spring means between said first and second cylinders resiliently biasing said cylinders in longitudinally opposed directions,

a piston connected to said first cylinder adjacent another end of said first cylinder defining with said cylinders first and second chambers,

said piston including a longitudinal bore providing communication between said chambers,

a cavity on one side of said head facing said first chamber,

a metering pin connected to said second cylinder for movement therewith and projecting from said first chamber through said bore into said second chamber,

said pin including at least one longitudinally extending metering flute,

a valve plate in said cavity having a metering orifice encircling said metering pin,

a casing having an accumulator chamber connected to said metering pin and being slidingly disposed relative to said second chamber,

Opening means providing communication with said second chamber and said accumulator chamber,

a second piston slidingly disposed in said accumulator chamber, and

means in said accumulator chamber biasing said piston toward said opening means,

said cylinders being movable during a buff impact from a neutral to a closed position whereby fluid flows from said first chamber through said metering orifice through said second chamber and to said accumulator chamber whereby said second piston is moved to compress said biasing means.

2. The invention in accordance with claim 1,

said second piston having one side facing one end of said casing and said opening means and an opposite side facing the other end of said casing,

said biasing means being disposed in said other end of said casing, and

means on said other end of said casing venting the same to the atmosphere.

3. The invention according to claim 1,

said casing including a cylinder having an outer cylindrical surface in sliding engagement with an inner cylindrical surface of said first cylinder, and

sealing means between said inner and outer cylindrical surfaces.

4. The invention in accordance with claim 3, including means connecting said casing to said metering pin comprising an apertured annular plate, said plate and casing being horizontally spaced from said first piston in the neutral position, and said casing being movable into close adjacent relation to said first piston during a draft impact.

5. The invention in accordance with claim 1, said casing including an apertured plate connecting said casing to said metering pin,

said plate in the neutral position being horizontally spaced relative to said first piston,

said plate being movable from said neutral position toward said first piston during a draft impact whereby fluid is moved from said second to said first chamber through said metering orifice.

6. The invention in accordance with claim 1, said first piston including a second cavity facing said second chamber,

a second valve plate slidingly disposed in said second cavity said second valve plate having an opening providing for the flow of fluid from said metering orifice to said second chamber during said buff impact.

7. The invention in accordance with claim 6, said second valve plate being movable during a draft impact to a position blocking the flow of fluid from said second chamber through said opening of said second plate, and

a second bore in said first piston providing for the flow of fluid from said second chamber through said first metering orifice to said first chamber during said draft impact.

8. The invention in accordance with claim 7, said second valve plate including means projecting into said metering flute and restraining the flow of fluid therethrough during relative movement of said cylinder during a buff impact.

9. The invention in accordance with claim 8, said projecting means comprising an element having a tongue conforming in shape to said metering flute and resilient means biasing said tongue into engagement with said flute whereby fluid flowing from said first chamber through said metering orifice passes through said opening of said second valve plate to said first chamber.

10. A hydraulic cushion device for railway cars comprising:

first and second cylinders connected in relative reciprocating sliding relation,

said cylinders being provided at their outermost ends with end plates,

a piston connected to an inner end of said first cylinder and providing with said second cylinder a first chamber disposed on one side of said piston,

said first cylinder including a second chamber provided on the opposite side of said piston,

said piston including a longitudinal metering bore,

a metering pin rigidly connected within said second chamber and extending through said bore,

said metering pin having at least one longitudinally extending flute of varying cross sectional area along the length of said flute,

said piston including a first cavity opening into said first chamber,

a valve plate having a metering orifice disposed in said first cavity and said metering pin being movable -through said orifice,

a second cavity in said piston including fluid by-pass means having a first longitudinal bore through which said metering pin extends,

said fluid by-pass means including an aperture,

means on said fluid by-pass means slidingly engaging said flute during movement of said cylinders toward each other to block the flow of fluid passing through said flute from said metering orifice and said first chamber, whereby said fluid is by-passed through said aperture to said second chamber.

11. The invention in accordance with claim 10, said blocking means including a movable element having a tongue complemental in shape to the configuration of said flute and being engaged therein, and

means biasing said tongue into said engagement. 

1. A hydraulic cushion device for railway cars comprising: a first cylinder having at one end a closure plate, a second cylinder having an open end and a second closure plate adjacent its other end, said second cylinder being slidingly disposed relative to said first cylinder, spring means between said first and second cylinders resiliently biasing said cylinders in longitudinally opposed directions, a piston connected to said first cylinder adjacent another end of said first cylinder defining with said cylinders first and second chambers, said piston including a longitudinal bore providing communication between said chambers, a cavity on one side of said head facing said first chamber, a metering pin connected to said second cylinder for movement therewith and projecting from said first chamber through said bore into said second chamber, said pin including at least one longitudinally extending metering flute, a valve plate in said cavity having a metering orifice encircling said metering pin, a casing having an accumulator chamber connected to said metering pin and being slidingly disposed relative to said second chamber, opening means providing communication with said second chamber and said accumulator chamber, a second piston slidingly disposed in said accumulator chamber, and means in sAid accumulator chamber biasing said piston toward said opening means, said cylinders being movable during a buff impact from a neutral to a closed position whereby fluid flows from said first chamber through said metering orifice through said second chamber and to said accumulator chamber whereby said second piston is moved to compress said biasing means.
 2. The invention in accordance with claim 1, said second piston having one side facing one end of said casing and said opening means and an opposite side facing the other end of said casing, said biasing means being disposed in said other end of said casing, and means on said other end of said casing venting the same to the atmosphere.
 3. The invention according to claim 1, said casing including a cylinder having an outer cylindrical surface in sliding engagement with an inner cylindrical surface of said first cylinder, and sealing means between said inner and outer cylindrical surfaces.
 4. The invention in accordance with claim 3, including means connecting said casing to said metering pin comprising an apertured annular plate, said plate and casing being horizontally spaced from said first piston in the neutral position, and said casing being movable into close adjacent relation to said first piston during a draft impact.
 5. The invention in accordance with claim 1, said casing including an apertured plate connecting said casing to said metering pin, said plate in the neutral position being horizontally spaced relative to said first piston, said plate being movable from said neutral position toward said first piston during a draft impact whereby fluid is moved from said second to said first chamber through said metering orifice.
 6. The invention in accordance with claim 1, said first piston including a second cavity facing said second chamber, a second valve plate slidingly disposed in said second cavity said second valve plate having an opening providing for the flow of fluid from said metering orifice to said second chamber during said buff impact.
 7. The invention in accordance with claim 6, said second valve plate being movable during a draft impact to a position blocking the flow of fluid from said second chamber through said opening of said second plate, and a second bore in said first piston providing for the flow of fluid from said second chamber through said first metering orifice to said first chamber during said draft impact.
 8. The invention in accordance with claim 7, said second valve plate including means projecting into said metering flute and restraining the flow of fluid therethrough during relative movement of said cylinder during a buff impact.
 9. The invention in accordance with claim 8, said projecting means comprising an element having a tongue conforming in shape to said metering flute and resilient means biasing said tongue into engagement with said flute whereby fluid flowing from said first chamber through said metering orifice passes through said opening of said second valve plate to said first chamber.
 10. A hydraulic cushion device for railway cars comprising: first and second cylinders connected in relative reciprocating sliding relation, said cylinders being provided at their outermost ends with end plates, a piston connected to an inner end of said first cylinder and providing with said second cylinder a first chamber disposed on one side of said piston, said first cylinder including a second chamber provided on the opposite side of said piston, said piston including a longitudinal metering bore, a metering pin rigidly connected within said second chamber and extending through said bore, said metering pin having at least one longitudinally extending flute of varying cross sectional area along the length of said flute, said piston including a first cavity opening into said first chamber, a valve plate having a metering orifice disposed in said first cavity and said meteRing pin being movable through said orifice, a second cavity in said piston including fluid by-pass means having a first longitudinal bore through which said metering pin extends, said fluid by-pass means including an aperture, means on said fluid by-pass means slidingly engaging said flute during movement of said cylinders toward each other to block the flow of fluid passing through said flute from said metering orifice and said first chamber, whereby said fluid is by-passed through said aperture to said second chamber.
 11. The invention in accordance with claim 10, said blocking means including a movable element having a tongue complemental in shape to the configuration of said flute and being engaged therein, and means biasing said tongue into said engagement. 